Skin is the largest organ of the human body, representing approximately 16% of a person's total body weight. Because it interfaces with the environment, skin has an important function in body defense, acting as an anatomical barrier from pathogens and other environmental substances. Skin also provides a semi-permeable barrier that prevents excessive fluid loss while ensuring that essential nutrients are not washed out of the body. Other functions of skin include insulation, temperature regulation, and sensation. Skin tissue may be subject to many forms of damage, including burns, trauma, disease, and depigmentation (e.g., vitiligo).
Skin grafts are often used to repair such skin damage. Skin grafting is a surgical procedure in which a section of skin is removed from one area of a person's body (autograft), removed from another human source (allograft), or removed from another animal (xenograft), and transplanted to a recipient site of a patient, such as a wound site. As with any surgical procedure, skin grafting includes certain risks. Complications may include: graft failure; rejection of the skin graft; infections at donor or recipient sites; or autograft donor sites oozing fluid and blood as they heal. Certain of these complications (e.g., graft failure and rejection of the skin graft) may be mitigated by using an autograft instead of an allograft or a xenograft.
One of the causes of graft failure is that a skin graft is applied to a recipient site having an improper orientation, i.e., the graft is applied such that the stratum corneum layer of the graft contacts the recipient site instead of the basal layer of the graft. This is a particular problem with an epidermal graft, because an epidermal graft has no blood vessels; thus, it must receive nutrients by diffusion from the underlying dermis through the basement membrane. A graft applied with an improper orientation will not receive nutrients and the cells of the graft will die, leading to graft failure.